Hikaru Wakaura

Recently there are more promising qubit technology such as Majorana fermions Rydberg atoms and Silicon quantum dot have yet to be developed for realizing a quantum computer than Superconductivity and Ion trap into the world The simulation of the quantum hardware of these qubits can only be done numerically However a classical numerical simulation is limited concerning available resources The method for simulation of quantum hardware by quantum hardware may be necessary In this paper we propose a novel method for optimizing time propagation from initial states to aimed given states of systems by the Born machine We call this method the Hamiltonian Engineering Born Machine HEBM We calculated the optimal Hamiltonians for propagation to Bars and Stripes distribution Gaussian distribution and Gibbs state for $H=-\Sum Z_j Z_{j+1}$ and revealed that they can be realized rapidly and accurately

The spin-vortex-induced loop current (SVILC) is a nano-sized loop current predicted to exist in the CuO$_2$ plane in the bulk of hole-doped cuprate superconductors. It is a persistent loop current protected by the topological winding number associated with the wave function. It exists around a spin-vortex created by the itinerant electrons with a doped hole at its center. The direction of each SVILC can be either clockwise (winding number is -1) or counterclockwise (winding number is +1) and the winding number with no current (winding number is zero) is forbidden by the singlevalued requirement of the wave function with respect to the electron coordinates. Recently, it has been demonstrated, theoretically, that this degree-of-freedom can be used for qubits. Coupling of neighboring qubits by external current feeding is confirmed to be realizable. This means that nano-sized couplers of SVILC qubits using feeding external currents are realizable. The size of couplers of SVILC qubits can be conparable or smaller than that of trapped ion qubits. Couper size of SVILC qubits is decided by the range of spin vortices in CuO$_2$ plane and current distribution, thus, this is tunable by feeding external current and substituting Cu atoms in barrier atoms. That of trapped ion qubits is limited by the distance that combined vibration occurs or laser range with respect to the coordinates. In the present work, We demonstrated splitting energy levels by external feeding current of three qubit system of SVILC qubits. This means that nano-sized qubit differentiator can be realized, and noise by static magnetic field can be cut off, and this may enable the realizing fully-fault tolerant quantum computers by SVILC qubits. Moreover, the possibility of downscaling of them is shown.

Observing rapid developments of both the number of qubits and quantum volume, especially with recent advances in ion-trap quantum computers, it is no doubt that Fault-Tolerant-Quantum-Computer (FTQC) will be realized in the near future. Since FTQC requires 10,000 physical qubits for every 100 logical ones, it will be used as the first large-scale Noisy-Intermediate-Scale-Quantum (NISQ) . The Variational Quantum Eigensolver (VQE) method will be used until large-scale FTQC with more than 100 logical qubits are realized. Therefore, the VQE method must be improved with respect to both accuracy and time to solution using large resource of the near FTQC . In this paper, we propose Tangent-Vector VQE (TVVQE) method to manage these issues. The method optimizes the norm of tangent vector of trial energy. We demonstrate the calculation of energy levels on Hydrogen molecule, Hubbard model, and Lithium Hydride molecule and reveal that TVVQE has a potential to calculate ground and excited energy levels more accurately than other VQE methods.